Receiver for systems of



LCDL-LED FIPEllO PATENTED MAY 7, 1907.

. L.'.I. BLAKE. I I RECEIVER FOR-SYSTEMS OF SUBMARINE SIGNALING.

APPLIOAT-ION FILED JAN. 29, 1907.

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LUCIEN I. BLAKE, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO SUBMARINE SIGNALCOMPANY, OF BOSTGN, MASSACHUSETTS, A CORPORATION OF MAINE.

Specification of Letters Patent.

Patented ma 7,1907.

zipplication filed Tannery 29.1907. Serial 110. 354.626. I

T /aZZ whom it may concern: v

Be it known that I, LUoiEN I. BLAKE, a

, citizen of the "United States, residing at Boston, in the county ofSuffolk and State 01- 5 Massachusetts, have inventedor discovered.certain new and useful Improvements in Receivers for'Systems ofSubmarine Signaling,

. 'of which'the following is a specification, ref- -.erence beinghad tothe drawings accompao nying and forming part of the same.

- As anunderstand'ing of the nature of the invention upon which mypresent application is based, involves a knowledge of the phenomenon ofresonance,. the following; statel5 ment ,of well recognized principlesis apposite. a v

The fundamental principle of acoustic resonance is reflection. In anyportion of a gaseous medium which is isolated,-by which term as usedherein is meant wholly or par- I tially confined by boundary walls ofany suitable ,material differing in its physical proper: ties from theinclosed medium,a reflection occurs at the surfaces oi the boundarywalls, of any acoustic disturbance-present in that medium. Thisreflected disturbance .will travel back and forth between the walls 'orboundaries. to produce a tone of definite pitch, dependent upon thevolume and shape 3 of the medium inclosed. The chamber or cavity formedby the boundary walls is called a resonance cavity. The methodot'exciting a given medium to resonance is immaterial.

It may be eil'cctcd by sound vibrations brought into it from an outsideand remote source, or by vibrations originating within the cavityitself.

It is not necessary in any of the tions of the principle hereinafterdescribed, 40 or in general, that the cavity be entirely surrounded byreflecting walls, for an opening may be left in the latter through or atwhich vibrations may be imparted to the medium Within the cavity andanother through which the regular-p6 iodic vibrations of the mediumaffected may be comnuinicated to any other medium without the boundariesof the cavity.- The function of the resonance cavity thus becomes areinforce-r of sound, whether received or produced.

' In all aerial-sound producers resonance chambers are the e sentialelements for givapplicaing intensity of sound. Their action isexemplified in the case oforganpipes and Whistles. In these the columnof air inclo sed within the walls of the resonance chamber is set intoregular, periodic or harmonic vibration at .the embouchureby eitherthe'socalled flute mouth-piece or' a reed. -When the length of the aircolumn is great in cornparison with its other dimensions, as in the caseof a pipe, the pitch is controlled by the period of travel of thedisturbance from end to end of the pipe, and this is called the freeperiod of the pipe. In the flute mouth-piece form a thiii jet of air orsteam impinges upon the sharp edge of an opening into the chamber and.the rhythmic effect of friction pro duces a vibrating reed of air orsteam. which is continually controlled in its rate of vibra tion by theregular periodic vibrationspf the column of air in the pipe.

In the case of the reed mouth-piece the reed is set in vibration by theair or st-eamimpinging upon its unconfined edge, and the or steam columnsustains and reinforces these vibrations,controlling their rate andconseq uently the pitch of the tone it the reed be not toostiff. Ineither case the free vibration'of the column within the pipe or chamsber is the essential source of sound.

In connection with the consideration of the action or effect of theseresonance cavities, it is iimpcu'tant to bear in mind the distinctionbetween the free vibration of the inclosed medium and the forcedvibrations which occur in consonant materials excited by any sourceofsound. in the phcnomenon of resonance, 'one definite .pitch isconspicuous or natural for each given set of conditions, while in thecase of consonance,

sounds of any pitch are reinforced. In the former the size and shape ofthe mass of-conlined medium control in determining the pitch, thecharacter of the containing walls, 5 within certain limits hereinaftermoreiullfexplained, being-immaterial provided they are capable ofreflecting, the disturbances; while in the latter, the physicalcharacter of the consonant body is the controlling consid- I03 eration,size and shape being. immaterial.

I have discovered and practically demonstrated that under properconditions a liquid. medium may be readily brought into sonorousresonance with a tone of given pitch, and that an isolated portion ofliquid medium possesses, according to its dimensions, a certain musicalpitch 1 of its own. lf, under such conditions, harmonic vibrations beset up within a body of liquid the latter may be caused to stronglyreinforce these vibrations and consequently intensify the duced by them.Such a liquid mass will also reinforce sounds delivered into itfrom adistancc, whereby weak tones will be rendered more audible, so that itmay, therefore, be

utilized, like an aerial resonator, both for the product on andreception of sounds. Availing myself of this discovery, I have employedliquid resonators in systems of-submarine signalin with results of ahighly useful and novel character.

The desirability of securing the advantages of resonance forintensifying sound, either produced for transmission 'or received fromadistant source, in the art otsubmarine signaling, has been recognizedby those skilled-in the art. As an abstract proposition it is,- in fact,self suggestive from analogous results in the application of the samebroad principle in the case of wind instruments, whistles, and ingeneral those devices in which a sound of given pitch is reinforced by aresonating body of air or gas. l lo useful or practical application ofthe principle to submarinesignaling, however, has ever been made, so faras i am aware, and for the reason, which my discovery has now renderedapparent, that conditions essential to the attainment of the resonanceof isolated bodies of liquid, have not been recognized or securedin anyapparatus that has been designed or proposed for use ,either asproducers or receivers of sound under water. In all wind instruments andother devices in whichthe resonance of a conlincd or isolated body ofair is utilized, the resonating medium is of such a highly compressiblenature in comparison with the n'iatcrials ordinarily constituting itsboundaries, that the latter may be of almost any rigid material, suchwood, paper or very thin metal. if,

however, the niediumwhich it is desired to set into resonance be aliquid, which is practically incompressible ascompared with any gas, therhythmic changes of pressure within it which correspond to sound, exertexceedingly powerful total pressures over the boundary walls of thechamber or cavity containing the liquid, according to the laws of.hydrostatics. Such pressures, as is well known,v may bend and even burstwalls of ordinary strength.' Therefore, if liquid resonators beconstructed without due regard to the effect upon theretainingwalls ofthese variations of hydrostatic pressure, they pre-- sent conditionswhich actually remove the elementsupon which rijection depends, but theefiect of which is negligible when the sound proas air. It is forthisreason. that a water col'- umn in an ordinary organ pipe does notproduceresonance. This may be conclusively demonstrated by the followingexperiments; if a pipe 4.- inches in cross sectional area and severalfeet long be made of hard metal, says of an inch thick, which would producevery much greater rigidity than would be required in any ordinarytone-producing instrument, ahd provided with an embouchure similar tothat of an organ. pipe, it may, if submerged in water, be operated toproduce a tone by a jet of water in the same manner as an organ pipe isoperated by air. it will be found, however, that the tone produced has apitch wholly independent of the length of the pipe, thus showing thatthe water column is not set in resonance. The reason for this, as I havefound, is that the rigidity of the Walls is not sutlicient to withstandthe variations in hydrostatic pressure t and thereby reflect the regularperiodic or i harmonic vibrations imparted to the mass of liquid'withinthe pipe. If the walls of the pipe yield, then any change in thepressure originating at the embouchure of the inclosed liquid'will beinstantly relieved at that point, and therefore no change in pressurewill be propagated through the pipe to un dergo reflection, and therebyto produce resonance. in short, the liquid column remains quiescent atits normal pressure, and i takes no part whatever in the production orreinforcement of sound. if the same pipe, however, be made of very hardand tough steel, with walls even more unyielding than. the practicallyincompressible Water surrounding them, it will be found to produce, whenoperated by'a water jet in the same way, a tone of definite pitch thatvaries with the length of the pipe, thus proving that the liquid masswithin the same is brought into resonance. To convey an idea ofwhat isrequired in securing the proper character of inclosing walls for aliquid resonator, it may be stated that air is over twenty thousandtimes more compressible than Water; and

than hard steel, so that to secure the requiresonator l have found itnecessary to build them up by shrinking very tough steel tubes upon oneanothe Applying the principle of the discovery that the boundary wallsof the chamber or cavity for aliquid resonator must be of this specialcharacter in order to'withstand the variations of hydrostatic pressure,and thereby produce the reflection characteristic of resonance, l hayeproduced apparatus for use in, systems of submarine signaling capableo'f intensifying sounds, both sent and rein submarine, work whichdistinguish si mjlar medium is an easily compressible gas, suc

water oversixty times more compressible site rigidity of the walls inthe case of a liquid ccived; an'd which possess all the advantagesdevices for aerial sound-producing and signaling purposes, and whichhave always been recognized and adopted as the most eflective forfogsignals, alarms and'similar purposes.

In an application filed by me on January 8th, 1907, Serial No. 351,561,I have illustrated. the application of the principle of res onance toboth sound producers and sound receivers for submarine systems, but haveconfined the more specificclaims to the former and to features ofnovelty that are common to both forms of instrument. In the presentapplication the claims are directed to those features of novelty which.more particularly distinguish the application of the principle to soundreceivers. I have, however,

.as a more convenient illustration olthe principle, shown in theaccompanying drawings, the sound producer of the application referredto.

Referring now to the accompanying drawings, Figure l is a view inelevation of the sound producer, showing the means for operating thesame. Fig. 2 isa longitudinal cross-section of-the operative parts ofthe same. Fig. 3 is a sectional view of the sound receiver in which theinvention upon which my present application is based, is embodied.

Referring to Figs. 1 and 2, A is'a cylinder of steel. it is shown asclosed at one end and with the other open end beveled on an angle "ofabout 60 degrees to sharp edges. It is-not necessary that the cylinderbe closed, but, as

- will be understood, to secure the same free the other.

the heads C, D, of a rigid frame. In, the

head C is secured, or integral with it is cast, a chamber E, provided.with an inlet, through which water is introduced by a pipe G from anysuitable source capable of de ivering it at a high pressure. Within thechamber E is a spider H carrying a plate K of slightly smaller'diameterthan an opening in the end of the chamber, and which therefore leaves ofan inch in width.

an annular orifice L preferably ot' about in the head. D is a circularopening with tlu'eaded walls with Which'corresponding threads on theexterior of the cylinder A engage';. B y this means the cylinder isrigidly supported with its beveled edge in proper position relative tothe annu lar orifice L and with the capability of adjustment withrespect thereto. The cylinder A is adjusted. to bring its edge.in closeproximity to .the annular oriliceTL, and is submerged at any desiredpoint. where the sounds or signals are to be produced. -Water underpressure, preferably from 125 to 200 pounds, is then supplied to thechamber E, and issuing therefrom in the form of an annular jet ilnoingesupon the edges and. beveled end of the cylinder A, with the resultthat'the harmonic or regular periodic vibrations are set up in thecolumn of water within the cylinder. These vibrations, (wing to the unyielding character of the bourn'laries of the chamber or cavity in whichthe column of water is contained. are reflected back and forth from thewalls and the column is therefore set in sonorousresonance. paratus willproduce a tone of definite pitch dependent upon the. dimensions of thechamher or cavity within the cylinder A. I have found that sounds thusproduced will be carricd to great distances through water and may bedetected and renderedflaudible by,

suitable sound receiving instruments the more readily because of theirdistinctive musical character. the pressure of the water supplied to thechamber E, or by deflecting the jet issuing from the orifice in saidchamber, distinctive signals, according to any prearranged code,

mgy be sent by tlns device.

By interruptmg or varying.

Such an ap- Fig. 3 which illustrates the device for' receiving sound Srepresents a portion of the skin ofa steel vessel, which is selected forurposes of illustration. To the inner surace of the skin is secured, asby means of bolts P passing throughflan es at its end, a

steel cylinder M of the same 0 a'racter as that described in connectionwith Figs. 1 and 2. Thegop osite' or inner end of-the cylinder M isclose by a head N of corres ondin thicl:- ness, the edges of which are teade to engage with threads in the inner surface of the cylinder. Asmall orifice V is formed in the head N and an ordinary microphonictrans mitter T is secured overthe same or placed at any point at whichit will be operated by the resonance of the column of water contained inthe cylinder M. Wires O, 0, connect the microphone with an ordinarytelephone receiver. A small opening B may be drilled through the shipsskin in order to permit access of the water into the cylinder M, butthis is not necessary for reasons previously described, as sounds comingthrough the water would be transmitted through the Wall of the shipto'the water column in the cylinder M, even were no pass-age of communi,The head N, by means ofcation present. its threaded connection with thecylinder M,

may be adjusted to vary the dimensions of' the chamber within thecylinder, and thus control the pitch of the resonant cavity in order totune it to any desired source of ,sound. In this device the column ofwater within the cylinder M will be set in resonant vibration by a givensound transmitted to it through. the water and entering eitherthroughmhe si ips wall. or the opening R.

IIO

The sound thus intensifi ed operates the microphone, which produces inthe telephone receiver an audible sound.

W'liile l have described theinvention by reference to a specific form ofapparatus, it is evident that its construction may be greatly varied. ingeneral, the sound receiver maybe submerged at any selected station orplaced in a tank attached to the walls of a vessel so that by means ofthe ap-' paratus signals may be transmitted from the shore to a vessel,or conversely, or between vessels within'the limits of practicaltransmission.

What I claim as my invention is:

l. A sound receiver for submarine signaling systems, comprising incombination a re ceptacle with walls capable of withstanding thevariations of hydrostatic pressure accompanying regular periodicvibrations in a body of liquid contained therein, and reflecting thesame to produce resonance,'and a sensitive I consisting of a receptaclewith walls 5 capable of reflecting regular periodic or harmonicvibrations set up in a body of liquid contained within the same, and amicrophonic sensitive device, secured over an ori-. fice in the end ofthe receptacle through 40 which the vibrations are caused to act uponthe sensitive'device, as set forth.

4. The combination of a liquidresonator consisting of a receptacle withrigid Walls capable of reflecting regular periodic or har- 4 5 monicvibrations set up. in a body of liquid 1 contained within the same, andsecured over an opening in the side of a vessel, and a microlphonicsensitive device secured over an ori co in the end of the receptaclethrough 50 which the vibrations are caused'to act upon the sensitivedevice, as set forth.

5. A sound receiver for submarine signalin systems, comprising incombination a. be low cylinder with Walls capable of With- '5 5 standingthe variations in by ostatic pressure accompanying the vibrationsimparted to a body of-liquid contained therein and reflecting the sameto produce resonance, a head adjustable in saidcylinder to vary the di 6mensions ol the chamber Within the cylinder, and a sensitive device inposition to be af* fected bythe vibrations of the body of liquid,

as set forth.

LUCIEN I. BLAKE. Witnesses V MAoALLAsrER MOORE, 1' J. CONVERSE GRAY.

